Reproductive research at the ORPRC includes studies in fetal endocrinology, uterine physiology, and neuroendocrinology as well as those supported in this program. Within this project our research emphasis include 1) transport and maturation of sperm, and the structure and function of the epididymis; 2) autoimmune response after long-term vasectomy; 3) the enzymic and hormonal regulation of energy metabolism in ejaculated and maturing spermatozoa; 4) the hormonal regulation of differentiation of the epithelium of the oviduct and epididymis; 5) receptor proteins in the oviduct; 6) the life cycle and dynamics of oviductal cilia; 7) the relationship of ovarian steroid secretion to follicular growth and ovulation and local changes in the oviduct; 8) the role of estrogens and androgens in the regulation of gonadotropins; 9) blood flow in the ovary and reproductive organs and the role of prostaglandins; 10) the role of androgens in sexual behavior and psychosexual differentiation; 11) factors that regulate the motivation of sexual behavior; and 12) the role of light on sexual cycles. Bibliographic references: Alexander, N.J. Immunologic effects of vasectomy in rhesus monkeys. In: PARFR Workshop on Control of Male Fertility (J.J. Sciarra, C. Harkland and J.J. Speidel, eds.). Harper and Row, New York, pp. 177-188, 1975. Tseng, M.T., N.J. Alexander, and G.W. Kittinger. Effects of fetal decapitation on the structure and function of Leydig cells in rhesus monkeys (Macaca mulatta). Am. J. Anat. 143:349-361, 1975.